| heal.abstract |
The study was carried out on five-year-old trees grown in the orchard of the Agricultural University of Athens. The cultivars studied were 'Kymis', 'Fracasana', 'San Pedro' and 'Politiko' (white cultivars) and 'Vasilika Black', 'Vasilika Melia' and 'Mission' (black cultivars). The rate of CO2 assimilation (Pn) and stomatal conductance (gs) were measured using a portable infra-red gas analyser. Fruit diameter and weight, fruit skin colour and firmness, pH and acidity, soluble sugar concentrations (by HPLC) and total soluble solids (TSS) were measured to evaluate fruit quality. Pn and g s significantly differed among cultivars. 'San Pedro' and 'Vasilika Black' showed the highest values while 'Politiko' the lowest. The mean fresh weight and fruit diameter were greater in 'Politiko' and 'Kymis', while 'Fracasana' had the smallest value. Fruit firmness was least in 'Vasilika Black' and highest in 'Politiko'. Juice acidity was similar in 'Fracasana', 'San Pedro' and 'Vasilika Melia' with much higher pH values than the other cultivars. Glucose, fructose and sucrose were the main soluble sugars found in mature fruits of all cultivars: glucose concentration was the highest in all cultivars followed by fructose, and sucrose at much lower concentrations. 'Fracasana' and 'San Pedro' had higher total soluble sugar concentrations than the other cultivars, while TSS was higher in 'Kymis' and 'Mission'. Pn was significantly linearly correlated with gs (r=0.724), and the total sugar concentrations in fruits (r=0.383), while total sugar concentrations were significantly correlated with TSS (r=0.311). 'San Pedro' was the earliest maturing cultivar, followed by 'Mission' and 'Politiko', while the latest maturing was 'Vasilika Melia'. |
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